Centralized traffic controlling system



Oct. 29, 1935. w. w. WENHOLZ CENTRALIZED TRAFFIC CONTROLLING SYSTEMFiled Jan. 28, 1951 INVENTOR ZU. 110m Patented Oct. 29, 1935 I UNITEDsTArss CENTRALIZED TRAFFIC CONTROLLING SYSTEM Walter W. Wenholz,Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application January 28, 1931, Serial No. 511,829

17 Claims.

This invention relates to centralized traffio controlling systems, andmore particularly to a system of the unit line wire type, asdistinguished from the system of the selector type.

In accordance with the present invention, it is proposed to control adistant switch machine over one line circuit, to control signalsassociated with the track switch operated by such switch machine overanother line circuit, and to indi- 101; cate whether or not the track isoccupied by a passing train and whether or not one of the varioussignals is indicating proceed, this through the medium of contacts atsaid track switch location, which open the line circuits used forcontrolling the switch machine and signals. It is of courseapparent thatif the clearing of a signal were to open the line circuit controllingsuch signal for indicating purposes, such signal could not be maintainedclear without the provision'of suitable stick means. Also, if theclearing of a signal were to be indicated over the circuit used forcontrolling the switch machine, this switch machine control circuitwould not be available for indicating the passage of a train over thegoztrack switch; also, switch machine operation could not be indicatedover the signal control circuit, because the signals must be held atstop to operate the switch machine.

In accordance with the present invention, it so, is proposed to indicateover the switch control circuit the occupied or unoccupied condition ofthe detector track circuit associated with the track switch, and toindicate over the switch machine control circuit both the occupancy of.535 this detector track circuit and the clearing of the signal, fromwhich it is apparent that, if the switch machine control circuit is openand the signal control circuit is closed, the switch machine controlcircuit must be open by reason of 49*; the fact that one of the signalsis at proceed.

Another feature of the present invention resides in the provision ofmeans for indicating an inconsistency between the signal control relayenergization and the indicating condition of the 415;, signal controlledby such relay.

' Other objects, purposes and characteristic features of the inventionwill in part be more specifically pointed out hereinafter, and will inpart be obvious from the accompanying drawing.

50:- In describing the invention in detail, reference will be made tothe accompanying drawing, which shows conventionally the circuits anddevices at an out-lying track switch location, and shows conventionallythat portion of the central 55 office equipment for controlling theswitch and signals at such location and receiving indications therefrom.

Referring to the drawing, the track rails of a railway system have beenshown by the reference character I, which rails are divide-d into 5track circuit sections by insulating joints 2. These track sections areeach provided with a track circuit in the usual way, of which thedetector track circuit containing the detector track relay DT and atrack battery 4 have only for w convenience been shown. Only a portionof the. railway signalling system has been shown in the drawing, whichportion includes one end of a passing siding PS and the end of a singletrack section 0. Traflic may move from the single 1 track section 0 intothe side track of the passing siding PS through the medium of a trackswitch SW, which is preferably power operated, as by the switch machineSM.

Although the signalling system to which the 20 present invention isapplicable may be a signalling system of the double track type, in whichtrafiic moves only in one direction oneaoh track, the invention has beenshown applied to a single track railway system in which traflic may move5 in either direction in response to signal indications, this singletrack section being signalled by a signalling system of theabsolute-permissiveblock type.

This A. P. B. system preferably includes a main starting signal I and adwarf starting signal 1 which signals govern the movement of traffic ofiof the main track and the side track, respectively, into the singletrack section 0, and

this track switch SW also has associated therewith a main enteringsignal 8 and a take-siding signal 8 These signals 1, 1 8 and 8 arecontrolled in accordance with trafiic conditions in advance, as throughthe medium of home-anddistance relays 'IHD and 8HD, and are further 40manually controlled by the signal control relay SZ, the main track andside track signals being selected in accordance with the position of amanually controlled switch machine control relay WZ and a switch machinerepeater relay WP.

In order to indicate through the same circuits used for controllingthese control relays SZand WZ the condition of occupancy of the.detector track circuit, as well as the initiation and completion of thestroke of the switch machine, a relay OS controlled through thefollowing circuit has been provided:beginning at the terminal or of theway station split battery, depending upon whether the switch machine SMis in its locked or in an intermediate position as manifested by theswitch machine repeater relay WP, contact Ill of this relay W'P, wirell, front contact it of the detector track relay DT, wire l3, winding ofthe relay OS to the midpoint C of said battery. This switch machinerepeater relay WP is energized by the following circuitzbeginning at theterminal or terminal depending upon whether the switch machine SMassumes the main track or the side track position, switch machinecontact !5, wire l6, winding of the relay WP to the midpoint C of theway station battery.

The switch machine SM is preferably cut out of service in the event thatcurrent has been flowing through the switch machine motor for too long atime or an excessive amount of current has been flowing through thisswitch machine, and for this purpose the cut-out relay CO and theassociated thermal relay TR have been provided.

Referring now to the central office equipment, this central office, ordispatchers ofiice, has been conventionally illustrated by the dottedrectangle DO, and in this central oflice the entire railway system ispreferably reproduced in miniature, as conventionally illustrated by theminiature passing siding ps corresponding in every detail to the actualpassing siding PS; In this central ofiice D0 are located the necessarylevers for controlling the various switch machines and signals, and inthe particular arrangement shown only the signal lever LS and the switchlever LW, and their associated-cont-acts and relays have beenillustrated. The signal lever LS is connected to the signal controlrelay SZ through the medium of the line wire 20 and includes in seriestherewith an indicating relay IE and the switch lever LW is connected tothe switch control relay WZ through the medium of a line wire 21, whichhas included in series therewith an indicating relay 1R located in thecentral ofiice DO. The indicating relay 1R has associated therewith aslow acting repeater relay RR which is slow to pick up.

The switch control lever LW is normally left in the main track position,in which it has been shown, and in which position the switch controlrelay WZ is energized toward the right through the following circuit:beginning at the terminal of the central office split battery, switchlever LW, wire 23, winding of the indicating relay 1R line wire 2i,front contact 24 of the relay OS, wires 25 and 25, back contact 2'! ofthe relay SZ, wire 28, winding of the relay WZ to the common return wireC connected to the midpoint of the central oiiice battery. Also, undernormal conditions of the apparatus the cut-out relay CO is energizedthrough the following circuit:-

beginning at the terminal of the way station battery, wire 3i contact 3!of the thermal relay TR, wire 32, winding of the relay CO, wires 33 and34, stick contact 35 to the other terminal of said battery. The currentthus flowing through element I05 is insufiicient to cause it to open thecontact 31.

Although the normal circuit for the switch machine including the normalwire N appears to be closed, this circuit is broken within the switchmachine SM, this switch machine preferably being one of the type shownin the patent to Howe No. 1,466,903 dated September 4, 1923, wherein theoperating circuits are broken upon completion of the stroke of theswitch machine. It is believedthat the novel features of the system aswell as its operating characteristics are more readily understood byconsidering the operation of the systemfwhich will now be taken up.

Operation It is, of course, understood that the track switch SW assumesits main track position, and let us further assume that there is an eastbound train moving in the single track section 0, and that the operatorwishes this train to move into the main track of the passing siding PS.In order to accomplish such east bound train movement, the operator willmove his lever LS to the right, thereby energizing the signal relay S2to its right hand energized position through the followingcircuitz-beginning at the terminal of the central office split battery,signal contact LS, wire it winding of the indicating relay 1R line wire2%, front contact ll of the relay OS, wire 52, winding of the relay SZ,through the common return wire C connected to the mid- 20 point of thecentral oflice battery.

The completion of this circuit will of course energize the relay SZ tothe right, thereby lifting its back contact 21 and opening the circuitfor the indicating relay IE and thereby allowing the contact 5 1 of theindicating relay IR? to drop to its retracted position and opening thecircuit (from minus, finger 44 and front point, wire 8|, lamp EI, wire80, lever 45, wire 19, finger lit and f-ront point, wire l3, lever H, toplus) for the eastbound indicating lamp EI, which circuit would havebeen closed through the medium of the signal lever contactde and thefront con. tact 46 of the indicating relaylR fromwhich it is apparentthat the east bound indicating lamp E1 is still extinguished. With thesignal relay SZ now assuming its energized position the signal it willbe cleared through the following cirdu'it:" beginning at the terminal ofthe way station battery, front contact 48 of the detector track relayDT, wire 49, front contact '50 of the relay SZ, wire 5!, polar contact52 of the relay SZ assuming its right-hand position, wires 53 and 54,polar contact 55 of the relay WZ, wire 56, neutral contact iii of therelay WP, wire 58', ,polar con,- tact 59 of the relay WP, wire"(ilL'neutral contact iii of the home-and-distance relay BHD, polarcontact 62 of the relay 'BHD, assuming its solid line or dotted lineposition depending on trafiic conditions ahead, and through the clear orcautionwire for the signal 8 conventionally shown by the dotted line 63.

Clearing of the signal 8, by the opening of its semaphore contact 66will break the energizing circuit for the signals-at-stop relay M, thecircuit for which relay may be traced as follows: beginning at theterminal of the way station battery, semaphore contact 61 of the signal1 closed only when this signal assumes the stop position, wire 68,signal contact 69 of the signal 1 closed only when this signal i is atstop, wire to, contact 66 of the signal 8, wire II, contact 12 of thetake-siding signal 8 closed only when this signal a is at stop, wire 13,windingof the relay M to the other terminal of the way station battery.g

The breaking of this 'circuitat the contact 66 causes the :relay M toassume its deenergized position, thereby eifecting closure of'itslbackrcontact i5 and effecting reenergization of the indicating relay 1R(through a circuit including plus, lever LW, wire 23, relay 1R wire 2|,finger 24 and front point, wire 25, finger I5 and back point, wire '28,relay WZ, to common) thereby completingthe following circuit for theeast bound indieating lamp EI:-beginning at the terminal of the waystation battery, contact H of the lever LW, wire 18, front contact 46 ofthe relay 1R wire 19, contact 45 of the lever LS, wire 88, indicatinglamp EI, wire 8|, front contact 44 of the relay 1R to the other terminalof said central oflice battery.

In response to this clearing of the signal 8, the train underconsideration may, of course, move from the single track section 0 intothe main track of the passing siding-PS. As this train passes the signal8 and treads upon the detector track circuit containing the track relayDT, this track relay DT is deenergized, thereby opening its contacts I2,48 and 65. Contact 98 is included in the clear and caution circuit forthe signal 8, so that the signal 8 will be actuated to its stopposition; the contact 55 is included inthe clearing circuit for thetake-siding signal 8 and the contact I2 of this relay DT by its droppingopens the energizing circuit for the relay OS, which in turn breaks bothof the line circuits 20 and 2| through the medium of its contacts 4| and24.

Simultaneous breaking of the two line circuits 20 and 2| causes theindicating relays IR and IR to simultaneously move to their deenergizedposition. Dropping of the indicating relay 1R effects extinguishment ofthe indicating lamp EI and energization of the slow acting repeaterrelay RR, but by reason of the slow acting characteristic of this relayRR its contact 83 will for a time remain in its retracted position,thereby momentarily completing the following circuit for sounding thebell, or other suitable audible sig-= nal, BL:beginning at the terminalof the central ofiice battery, contact ll of the switch control leverLW, wire I8, back contact 3-6 of the relay 1R wire 84, back contact 85of the relay 1R wire 88, back contact 83 of the repeater relay RR, wire87, bell cut-out key 88, wire 89, winding of the bell BL, to the otherterminal of said central office battery. Completion of this circuitsounds the audible signal BL and after a short period of time thecontact 83 will have been operated to its attracted position, therebycompleting the following circuit for the detector track circuitoccupancy lamp I:-begin.ning at the terminal of the central oflicebattery, elements 11, 18,46, 84, 85, 86, 83, and 99, track occupancyindicating lamp I, to the other terminal of the central office battery.The operator at the central ofiice is therefore informed by theextinguishment of his east bound indicating lamp EI that the signal 8has been moved to the stop position, and has further been informed bythe sounding of the audible signal BL and the illumination of theindicating lamp I that the train in question has entered upon thedetector track circuit containing the track relay DT.

As soon as the rear end of the train under consideration passes off ofthis detector track circuit the delay OS is energized and the contacts4| and 24 are reclosed. Reclosure of the contact 9| effectsreenergization of the relays IR and SZ, but reclosure of the contact 24will not effect reenergization of the relays IR and WZ, because thesignals-at-stop relay M is now again energized, the signal 8 having beenmoved to stop, so that the contact I5 of this relay M is open, as isalso the contact 2'! of the relay SZ, so that the indicating relay IRremains deenergized. With the relay IR in the central office DOdeenergized and the indicating relay IR in the central oflice DOenergized, none of the indicating lamps I,

WI or EI in the central ofiice can be illuminated, as is readilyapparent by observing the circuits for these indicating lamps.

As soon as the train in question has moved beyond the danger distancesignified by the stop 5 position of the home-and-distance relay 8HD,this signal 8 will be moved to caution, and with the signal 8 at cautionthe opening of its contact 66 will effect deenergization of the relay M,thereby reclosing the circuit including the line wire 2| 1 and effectingreenergization of the indicating a relay 1R With the indicating relaysIR and IR both energized the east bound indicating lamp E1 is againilluminated through the medium of the circuit heretofore traced. Fromthe fore- 15 going consideration it is apparent that a continuingindication of the occupancy of the detector track circuit containingtrack relay DT is indicated by continued illumination of the trackoccupancy indicator lamp I, and that the g0 movement of any one of thesignals I, I 8 and 8 from the stop position is continuously indicated bythe indicating lamps WI or E1 depending uponthe direction governed bythe signal which is assuming a proceed position. Further, it will be 25noted that the signal 8 could not be cleared or operated to cautionunless the relays WZ and WP, which respectively control, and arecontrolled by, the switch machine SM, assume corresponding positions.

For a train moving in a westwardly direction from the main track of thepassing siding PS into the single track section 0, the operation of theapparatus is identical to that just considered, except that thepolar-neutral signal control relay SZ is energized to its left handposition, thereby completing the following energizing circuit for thesignal 'lz-beginning at the terminal of the way station battery, frontcontact 48 of the detector track relay DT, elements 49, 50, 5|, 52, 4092, 93, 94, 95, 98, 91, 98, 99, I89, the caution or clear wire for thesignal I conventionally'indicated by the dotted line IOI, to the otherterminal of the way station battery.

Let us now assume that there is a west bound train on the side track ofthe passing siding PS and that the operator, or dispatcher, wishes toallow this train to proceed into the single track section 0. Theoperator will of course first place the signals in the stop position byoperating the signal lever LS to its middle position, this in order toallow certain time or approach locking means to function to permitoperation of the switch machine, this time or approach locking meanshaving for convenience been omitted from the drawing, but being shown inthe prior application of Wight Ser. No. 120,423 filed July 3, 1926. Theoperator will then move his switch lever LW to the dotted position, andthereby will operate the switch control relay WZ to its left hand dottedposition through the circuit heretofore traced, except that this circuitis now energized by current of negative polarity.

With the polar-neutral switch control relay WZ operated to its left handposition, the following circuit for operating the switch machine SM toits reverse take-siding position is closed:--beginning at the terminalfront contact I03 of the relay CO, wire I84, heating coil I05 of the ofthe switch machine SM to its take-siding position,sandwhen the switchmachine SM has completed its operating stroke and has been locked up thecircuit just tracedis again broken by contacts associated with theswitch machineiitself. The contact l5 in theswitchmachine is moved to anintermediate position upon initiation of movement of the switch machineand remains in the intermediate position until "the switch has completedits operating stroke and has again been locked up, at which time thiscontact assumes its other extreme position, so that the switch machinerepeater relay WPis deenergized as soon as the switchmachine SM isinitiated upon its operating stroke.

'This dropping of the relay WP reverses'the direction of current flowthrough the relay '05, so that this relay OS is momentarily deenergizedbecause the magnetism within its core structure must pass through zeroand thereby momentarily drop its armature. This momentary dropping ofthe armatureof the relay OS efiects momentary opening of the "contacts24 and 4l,but since the signal lever LS is in its intermediate positionthe opening of the contact'M serves no'function at this time. Momentary:opening of the contact 24 will eifect momentary deenergization of theindicating relay "IE and this momentary deenergization of the indicatingrelay IE 'will effect momentary sounding of the audible signal a BL andmomentary flashing of the indicating lamp I, all for reasons heretoforeexplained and stating it'briefiy is accomplished by dropping of thecontact 8'5 of the relay IR and picking up of the contact 83 of therepeater relay RR, there being a slight additional delay in theoperation of the contact 83 after operation :or the contact '85. Also,if desired the relay RR. may be sufficiently slow acting as comparedwith the relay OS that no flash of the lamp I is-given-at this time. Asthe switch machine completes its operating stroke the switch machinerepeater relay WP is reenergized, but at this time is energized to itsleft hand position, and the reenergization of the relay WP againeifectsmomentary deenergization of the relay OS, this becausethedirection of current flow in the relay OS is again reversed.

The operator having now been informed of the completion of the stroke ofthe switch-machine, and since, as has been assumed, he desired to set upwest boundtrafiic off of the si'de track of the passing siding PS,hewill operate' his-signal lever LS to the lefthand position, therebyenergizing the signal relay SZ to its left hand energized position,under which condition "the follow- 'ing circuit for the dwarf startingsignal I is -closed:beginning at the "terminal of the way stationbattery, front contact 48 of the detector track relay DT,"elementSlQflSDQ-B I 52,"-92,

IH, '91, 96, 95, 94, ll2,"frrit contact l'l'iof the 'home-and-distantrelay II-ID, polar contact "114 of this same relay throug'hthe clear orcaution wire for the dwarf signal'l depending on theex- 'tent ofunoccupied track ahead as manifested by the position of the polarcontact N4 of thewrelay 'IHD, through the mechanism of the dwarf:signal'1' ,'to the other terminal of "the way station battery.

Clearing of this signal "i will allowthe train to move off of the sidetrack into thesingle track section 0, and this movement of the trainwill be indicated through the medium of the track occupancy indicator Iin the central ofiice DO,

*andalso the clearing o'f'the signal I will bein- "clicated at thecentral ofiice -through the medium of indicating relay 'IRP.

of the west bound rindicatorWI, this signal lamp WI'beingcontrolledthrough'the medium of the wire '-I I5 insteadof wire "80of'the circu'rtahenetofore traced for the indicating lamp :EI. 'Itiisreadily illIldBI'StOOdthLt the take-siding signal :8 5 is controlled in-accordance with the positionof the relays SZ, WZ and WP and inaccordance with theipositioniof'the contact'iiE of :the detector trackrelay'DT, all a manner readilyfindicated by the contacts of thesevarious relays. Attention is particularly directed to the-fact that noneof the signals 'l, i -8, or 8 can be clear unless the relays WZ and "WP,respectively 'controllingyand controlled 'by, the switch machine iSM,assume corresponding positions. ;'It will be noted that fthese'varioussignal circuits include neutral contacts of the switch machine relay WPbut do not'inclu'de neutral contacts of .the switch machine controlrelay WZ; theneutral contacts of'the relay WZ have been omitted 'forthereason'that the relay WZ =is'at timesndeenergized, as "for instancewhenthe signals are at stop and the contact'15 of the relay'Miassumesits raised position. Further w'ithrelayiSZ 'energized'to clear a signalthe contact Tlisopen, 5 under which condition it is apparent thatthesignals could not be cleared if neutral front-contacts of the relay WZwere included'in the :signal control circuits. The signal circuits are.so organized'that polar contacts of .the'relays -WZ and "WP must assumecorresponding positions, so'that if the switch machine should notcomplete its stroke or s'houldnot at all'respond to a change in'theposition of its control relay WZ, it would result .in holding all .ofthe signals as-- sociated with the track switch SW at stop.

Applicant has thus provided acircuit arrangement in which the conditionof'track occupancy is transmitted over one line circuit, namely throughthe medium of the indicatingrelay IE o and the condition of :trackoccupancy as well as the condition of signal clearingis indicated overanother line circuit, as through the medium It is therefore ,possibletointerpret at the central oifice the indicat- 5 ing condition of'thesignals located at'the distant track switch, this by comparing "the':indications received over the two line circuits, -which comparison isaccomplished'through the medium of the slow acting repeater relay RR andthe V various contacts associated with the relays/IR},

IE and RR.

Having thus shown and described one rather specific embodiment of thepresent invention, it is desired to be understood that the particularcircuit arrangement illustrated in the drawing has not been selected forthe purpose OfiShOWiIlg the scope of the invention, nor has'itbeeniselected for the purpose of illustrating the eonclaims.

What I claim asnew is:-- I. In a centralized traffic controlling system,

in combination, a central officeianda distantztrack 5 switch, signalsassociated with said track switch, a switch machine ior operating saidtrack switch, aiswitch control circuit including the contact of a leverand for controlling said switch machine, r5 9. signal control circuitincluding the contact of a second lever and for controlling saidsignals, means for indicating occupancy of a section including saidtrack switch over said signal control circuit, and means for indicatingover said switch control circuit the proceed condition of 'a signal whena section including said track switch is unoccupied.

'2. In-a centralized traflic controlling system, the combination with acentral ofiice and a dis- ]5? tant track switch, signals associated withsaid track switch, and a switch machine for operating said track switch,of a switch control line circuit including a contact of a lever and forcontrolling said-switch machine, a signal control line circuit includinga contact of a second lever and for controlling said signals, means insaid central office for indicating the continuity of said signal controlcircuit, means in said ofiice for indicating the continuity of saidswitch control circuit, means 255: for opening said signal controlcircuit during occupancy of a section including said track switch, andmeans for opening said switch control circuit when all of said signalsindicate stop and the section including said track switch is unoccupiedproviding said signal control circuit is energizedJ g '3. In acentralized traffic controlling system, in combination, a centralofiice, and a distant track switch, signals associated with said trackswitch,

351: a switch-machine for operating said track switch, a switch controlline circuit for controlling said switch machine, a signal control linecircuit for controlling said signals, means in said central office forindicating the continuity of said sig- 40' nal control circuit, means insaid office for indicating the continuity of said switch controlcircuit, means for opening said signal control circuit during occupancyof a section including said track switch, a signal control relay in saidsiga.nal control circuit,- and means for opening said switch controlcircuit when said section is unoccupied and also said signal controlrelay is out of correspondence with the signal controlled by said signalcontrol relay.

59?; 4. In a centralized traffic controlling system,

the combination, with a central oiiice and a distant track switch,signals associated with said track switch, and a switch machine foroperating said track switch, of a switch control circuit Gincluding aswitch lever contact and for controlling said switch machine, a signalcontrol circuit including a signal lever contact andfor controlling saidsignals, means for indicating occupancy of a section including saidtrack switch toe over said signal control circuit, and means effectiveif said signal control circuit is energized to clear one of said signalsand to render said switch control circuit effective to indicate if suchsignal has been cleared.

5. In a centralized trafiic controlling system,

the combination with a central office and a distant track switch,signals associated with said track switch, and a switch machine foroperating said track switch, of a switch control line circuit includinga switch lever contact and for controlling said switch machine, a signalcontrol line circuit including a signal lever contact and forcontrolling said signals, means for opening said switch control circuitwhen all of said signals indicate stop, means for opening said signalcontrol circuit when said track switch is occupied by a train, asignal-at-proceed indicator at said central ofiice rendered effectivewhen neither of said control circuits has been opened, and a trackswitch occupancy indicator 5 rendered effective if both of said linecircuits have been opened.

6. In a centralized trafiic controlling system, the combination with acentral ofiice and a distant track switch, signals associated with said10 track switch, a switch machine for operating said track switch, aswitch control line circuit for controlling said switch machine, asignal control line circuit for controlling said signals,

both of said line circuits have been opened, and

means for selecting a particular one ofsaid two indicators depending onthe position of a control 25 lever for controllingenergization of saidsignal control circuit.

7. In a centralized traflic controlling system, the combination with acentral oiiice and a distant track switch, a signal associated with said30 track switch, a switch machine for operating said track switch, aswitch control'circuit including a switch lever contact and forcontrolling said switch machine, a signal control circuit including asignal lever contact and for controlling-35 said signals, and means forindicating occupancy of a track section including said track switch oversaid signal control circuit.

8. In a centralized trafiic controlling system, the combination with acentral office and a dis-' 4g tant track switch, signals associated withsaid track switch, and a switch machine for operat. ing said trackswitch, of a switch control circuit including a switch control lever andfor controlling said switch machine, a signal control cir- 45 cuitincluding a signal control lever and for controlling said signals, andmeans for indicating over said switch control circuit the proceedcondition of a signal when a section including said track switch isunoccupied. 1

9. In a centralized trafiic controlling system, the combination with acentral ofiice and a distant track switch, a signal associated with saidtrack switch, a switch machine for operating said track switch, a switchcontrol circuit including the contacts of a switch control lever forcontrolling said switch machine, a signal control circuit including thecontacts of a signal control lever and for controlling said signals, andmeans for indicating over said signal control circuit the 50 initiationof operation and the completion of the stroke of said switch machine.

10. In a centralized trafiic controlling system, the combination with acentral oflice and a distant track switch, signals associated with said5 track switch and a switch machine for operating said track switch, ofa switch control circuit controlled by a track switch lever and forcontrolling said switch machine, a signal control circuit including thecontacts of a signal con- 70 trol lever and for controlling saidsignals, and means for indicating over said switch control circuit thefact that said signal control circuit is energized and a signal hasresponded to such energization. 75

11. In a control System for railway switches and signals, thecombination with a local office and a distant way station, apower-operated railway track switch at said way station, a signal forgoverning traffic over said track switch, a lever in said ofiice forcontrolling said track switch, a lever in said office for controllingsaid signal, and an indicator in said office controlled to be energizedwhen said signal is clear and including an energizing circuit closedonly if said switch machine lever assumes an operating position and saidsignal lever assumes a signal-clear position.

12. In combination, a track section including a railroad track switch, asignal for governing trafilc over said track switch, a switch machinefor operating said track switch, a switch control lever, a signalcontrol lever, a switch control circuit energized in accordance withsaid switch control lever for governing the operation of said switchmachine, a signal control: circuit energized in accordance with saidsignal control lever for governing the operation of said signal, andmeans opening .both said switch control circuit and said signal controlcircuit to indicate an occupied condition of said track section,

13. In combination, a track section including a railroad track switch, asignal for governing trafilc over said track switch, a switch machinefor operating said track switch, a switch control lever, a signalcontrol lever, a switch control circuit energized in accordance withsaid switch control lever for governing the operation of said switchmachine, a. signal control circuit energized in accordance with saidsignal control lever for governing the operation of said signal, meanscontemporaneously opening both said switch control circuit and saidsignal control circuit when said track section is occupied, and meansresponsive to the open condition of both of said circuits to indicatewhen said, track section is occupied. V

14. In combination, a track, switch, a signal for governing traffic oversaid track switch, a switch machine for operating said track switch, aswitch control lever, a signal control lever, a normally energizedswitch control circuit which is energized in accordance with theposition of said switch control lever for governing the operation ofsaid switch machine, a signal control circuit energized in accordancewith said signal control lever for [clearing said signal when saidcircuit is energized, means opening said switch control circuit whensaid signal control circuit is initially energized, means for reclosingsaid switch control circuit when said signal has cleared in response toenergization of said signal control circuit, and means responsive to theenergization of both of said control circuits for indicating the clearcondition of said signal.

15.v In combination, a track switch, asignali for governing traffic oversaid track switclna: switch machine for operating said track switch,

a switch control lever, a signal control lever, a: normally energizedswitch control circuit which 5 is energized in accordance with thepositizm or said switch control lever for governing the opera;- tion ofsaid switch machine, a signal control cir cuit energized in accordancewith said ml: control lever for clearing said signal when said; 10circuit is energized, means opening said switch control circuit whensaid signal control circuit is initially energized, means forreclosingisaidv switch control circuit when said signal: has cleared inresponse to energization of said signal! 15 control circuit, meansalways effectivetos opens both said control circuits upon the occupied;more dition of a track section associated with said track switch, meansresponsive to the energize,- tion of both of said control circuits forindicating 20' the clear condition of said signal, and means.reisponsive to the deenergization, of both. of. said control circuitsfor indicating the occupied cone dition of said track section.

16. In combination, a track switch, a switch 25, machine for operatingsaid track switch, aiswitclr control lever, a normally energizedswitch.- con-- trol circuit which is energized in accordancewitlr theposition of said switch control lever for gov.- erning said switchmachine, over-load means. tor 30 said switch machine effective to remove1311816011 trol of said switch machine from said: switch: controlcircuit when an over-load condition occurs.

a detector track section associatedv with said: track switch, meanseffective upon the occupied. u-r. condition of said track section toopen said switch control circuit, means responsive to the deenergizationof said switch control circuit to restore the control of said switchmachine to said switch. control circuit, and. means responsive to thede- 4 energization of said switch control circuit to indicate at saidswitch control, lever the occupied condition of said detector tracksection.

17. In combination; a track section including a railroad track switch;asignal for governing trafiic over said track switch; a switch machinefor operating said track switch; a. switch control circuit for governingthe operation of said switch machine, said circuit including a currentsource, lever contacts, a switch control relay and con- 5 necting wires;a signal control circuit iorgoverning operation of said signal, saidcircuit inclu.ding a current source, lever contacts, a signal con.- trolrelay and connecting wires; means opening said switch and signal controlcircuits when said track section is occupied; and means responsive tothe contemporaneous deenergization of both said control circuits toindicate the occupied condition of said track section.

- WALTER W. WEN'HOLZ, I,

